In recent years, in order to solve the problem of increasing shortage of energy resources and reduce pollution caused by production of energy, green energy technologies have been developed aggressively. Solar cells can be installed with less location restrictions and energy source can be acquired easily, thus have been developed by a lot of enthusiasts. Thin film solar cells have the characteristics of low cost and mass production, hence grow rapidly in the market. Moreover, thin film solar cells can be formed on a wide variety of substrates, such as glass, plastics, ceramics, graphite, metal sheets and the like, with less restriction in use, and also can be formed on pliable substrates to further improve use flexibility. In addition, a thin film capable of generating electric voltage requires only a thickness of a few micrometers, thus consumes less material compared with silicon wafers which have to be maintained at a certain thickness. In order to be installed outdoors at a larger size to capture more solar energy and equip with required strength and transparency, the conventional thin film solar cells are commonly use glass as substrate, thereby to save more electric power expense and reduce carbon footprint.
U.S. Pat. No. 7,259,321 entitled “METHOD OF MANUFACTURING THIN FILM PHOTOVOLTAIC MODULES” discloses a method of manufacturing thin film solar cell. Its module uses an opaque metal layer that has undesirable transparency. As the opaque solar cell module blocks user's vision, its applications are limited to rain sheds, awnings, house roof or the like, and cannot be extended to the windows of the buildings. To improve indoor lighting and increase added value of the thin film solar cells adoptable to the windows, the thin film solar cells are generally formed with a patterned light permeable zone by laser beams. The light permeable zone can increase the aesthetic appeal and artistic value of the windows. Moreover, the light permeable zone provides greater transparency and improves indoor lighting.
However, the conventional light permeable zone is formed by ablating the thin film solar cells with a laser beam controlled by a computer in a switching manner. Resolution is less desirable. Moreover, frequent switching of the laser beam easily damages laser equipment and results in a shorter lifespan. In addition, laser operated in the switching manner can only display black and white patterns and is unable to display grey scale patterns. To form colored patterns on the thin film solar cells also is not possible. As a result, it is difficult to increase their added value and usability. In short, to improve the resolution of patterns and display grey scale or colored patterns become one of goals actively pursued in the industry of thin film solar cells.